This invention relates to the field of mechanical grasping devices and subassembly articles of manufacture used in constructing grasping devices. More specifically this invention relates to grasping devices and subassemblies having at least one multiply-segmented arm structure for grasping. The invention also relates to vehicular grasping devices.
In prior art grasping devices, such as the one schematically illustrated in FIG. 12, an inner arm 170 is pivoted to an outer arm 180. The outer arm 180 would swing uselessly on inner arm 170 but for a link 160 which enables the outer arm to help grasp an object 195 when a force 190 is applied.
Unfortunately, such prior art grasping devices must utilize the relatively long inner arm 170 and link 160 which are prone to bending and buckling with heavy loads precisely due to the long length. This problem rapidly increases in severity with increase in size and weight of the load because such load requires greater bending and buckling strength but perversely requires the larger arm and link lengths that reduce bending and buckling strength. Strengthening the prior art grasping devices with additional material, of course, increases their cost.
Inner arm 170 and link 160 of the prior art cross over each other, so that each is physically in the way of the other relative to an object 195 in the grasping region. Thus, an inherent limitation on the size of the object to be grasped is placed on the prior art device. In addition, the crossover complicates construction that further increases cost. When substantial extra material is added to the inner arm to permit an object to be grasped without bumping the link, the size and weight capacity of the grasping device is reduced.
Also, the crossover construction of the prior art can lead to mechanical rubbing and binding-up problems between inner arm and link under heavy loading transverse to the plane of the prior art device (perpendicular to plane of paper of FIG. 12). For this additional reason the crossover complicates construction and leads to mechanical strength limitations.
The background of the invention is further suggested by reference to a very specific field of vehicular collection application.
This invention relates to mobile refuse collecting devices, and particularly to a container grasping device adapted to be mounted on a vehicle for grasping, lifting, and emptying a refuse container into the storage portion of the vehicle.
The present methods and devices for collecting refuse are time consuming and labor consuming. Normally, a refuse collection vehicle drives through the community, and several laborers are required to lift the containers at each residence, and empty them into the storage portion of the vehicle.
Various attempts have been made to automate the grasping, lifting and emptying of the containers. However, several problems have been encountered with such devices. The containers in which the public store refuse often vary in size and shape, and therefore problems develop in designing apparatus which can readily grasp containers of varying sizes and shapes.
Often the containers are placed in positions difficult to reach with mechanical apparatus. For example, they may be resting upon a curb, in a snow bank, or on a level which is difficult to reach with apparatus attached to the vehicle.
Another problem is the difficulty in positioning the vehicle the proper distance from the container. It is desirable to have apparatus which can compensate for different distances between the vehicle and the container so that the vehicle driver does not need to worry about positioning the vehicle at the exact proper distance from the container.